This invention relates to an input apparatus adapted to be mounted on a machine equipped with a plurality of actuator driving circuits such as a civil engineering equipment, a construction equipment or the like. Also, the present invention relates to an input apparatus adapted to control its output by means of an external signal input thereto as well as by operation through its own control section.
In general, manual operation of a hydraulic driving circuit equipped with a plurality of actuators and arranged in a machine such as a construction equipment or the like has been conventionally carried out by means of a hydraulic joy stick which is a kind of input apparatus.
Such an input apparatus is generally constructed in such a manner as shown in FIG. 1. More particularly, the input apparatus which is a hydraulic type includes a body 10 and a control lever 12 mounted on a central position of an upper portion of the body 10 so as to act as a control section. The control lever 12 is arranged so as to be inclinedly moved in two directions perpendicular to each other or X and Y directions. Also, on the body 10 are four push rods 14, which comprise one set of two push rods 14 arranged in an X direction and the other set of two push rods 14 arranged in a Y direction perpendicular to the X direction. Each set of push rods 14 corresponds to each one actuator (not shown). Thus, it will be noted that the input apparatus shown in FIG. 1 is so constructed that the single control lever 12 operates two actuators.
The body 10 is formed therein with a chamber 16 in correspondence to each of the push rods 14 in a manner to be positioned below the push rod. In each of the chambers 16 is arranged a block 18, which is operatively connected at an upper end thereof to the push rod 14 and provided on a lower end thereof with a plate 20. To the plate 20 is operatively connected a spool 22 in a manner to be vertically movable, which spool 22 is formed in a lower portion thereof with a passage 24. The passage 24 is formed at an upper portion thereof with a port 26 which communicates with an exterior of the input apparatus as described below.
The spool 22 has a support member 28 securely fitted on an intermediate portion thereof. Another support member 30 is fixedly arranged on the above-described lower end of the block 18 in a manner to surround the plate 20. Each of the chambers 16 is also provided therein with a coiled spring 32 so as to be interposedly arranged between the support member 30 and a bottom of the chamber 16. Another coiled spring 34 is arranged between the support member 28 and the support member 30 and is positioned inside the first spring 32. Another coiled spring 36 is arranged inside the coiled spring 34. The body 10 is formed with a pump port 38, as well as a hydraulic oil feed passage 40 communicating with the pump port 38. Also, the body 10 is provided at a portion thereof below each of the spools 22 with an output port 42 communicating with an actuator (not shown).
In FIG. 1, only two push rods 14 and the construction associated therewith are shown, however, the other two push rods (not shown) are constructed in the same manner.
Now, the manner of operation of the conventional input apparatus constructed as described above will be described hereinafter.
Supposing that the control lever 12 is operated to force downward the push rod 14 shown on the right side in FIG. 1, the push rod 14 is moved downward to compress the coiled springs 32 and 34 through the plate 20 and support member 30 and downward push the spool 22. Such lowering of the spool 22 permits the port 26 of the spool 22 to communicate with the hydraulic oil feed passage 40, resulting in pressure or hydraulic oil being discharged through the port 26, passage 24 and output port 42 to the actuator (not shown). Also, such flowing of the hydraulic oil concurrently leads to generation of force which causes the spool 22 to be forced upward. The force thus generated is balanced with elastic force of the coiled spring 34, so that a pressure under which the hydraulic oil is discharged through the output port 42 is determined in association with the push rod 14.
The above-described operation is likewise carried out also when the control lever 12 is further operated in the same direction to compress the coiled spring 36. In this instance, elastic force of the coiled springs 34 and 36 and the above-described force for upward biasing the spool 22 are balanced with each other.
Unfortunately, the above-described construction of the conventional input apparatus restricts the apparatus to generation of only a hydraulic signal. Thus, it requires an electrical input apparatus separate from the hydraulic input apparatus when it is desired to control an electrical actuator actuated by an electrical signal, in addition to controlling of a hydraulic actuator by a hydraulic signal.
Also, even when it is possible to provide such an electrical input apparatus separate from the hydraulic input apparatus as described above, an operator must be skilled in order to concurrently operate both input apparatus in association with each other.
A conventional input apparatus of another type is shown in FIG. 2, which is constructed in the form of a pilot valve used for various industrial equipments. The input apparatus of FIG. 2 includes a body 100, which is formed therein with four chambers 102 as in the apparatus shown in FIG. 1, although FIG. 2 shows only two such chambers. The chambers 102 each are continuously formed at a lower portion thereof with a passage 104 and an output port 106 in a manner to communicate with each other. In the chamber 102 is arranged a shaft member 108 which is vertically movable therein. The shaft member 108 is fittedly provided on an outer periphery of an upper end thereof with a support member 110 and on an outer periphery of a lower end thereof with a support member 112, and between both support members 110 and 112 is interposedly arranged a coiled spring 114 acting as a part of elastic means. Also, the chamber 102 is provided therein a further support member 116 in a manner to be positioned below the support member 112, and between the support member 116. At a lower end or bottom of the chamber 102 is arranged a compression spring 118 in the form of a coiled spring so as to serve as another part of the elastic means. The remaining three chambers are constructed in the same manner.
The input apparatus also includes a push rod 120 vertically movably arranged above each of the shaft members 108. Above the four push rods 120 is commonly arranged a press member 122 acting as a part of a control section, and to the press member 122 is operatively connected a lever 124 acting as another part of the control section. The push rods 120, the press member 122 and a lower portion of the lever 124 are surrounded with a bellows-like cover 126.
In each of the passages 104 is arranged a shuttle 128 in a manner to be vertically slidable therein. The shuttle 128 is provided on a side wall thereof with a pair of upper and lower passages 132 and 130, respectively in a manner to laterally extend and be vertically spaced from each other and also provided therein with a vertically extending passage 134 so as to communicate with the lateral passages 130 and 132. The vertical passage 134 is arranged so as to communicate with the output port 106. In addition, the body 100 is formed therein with a pump passage 136, to which a hydraulic pump 138 is connected. The body 100 is also formed therein with a tank passage 140, to which a tank 142 is connected. FIG. 3 shows a circuit of the input apparatus or pilot valve thus constructed.
In the pilot valve constructed as described above, supposing that the lever 124 is operated to forcedly lower the push rod 120 shown on the right side of FIG. 2, the push rod 120 is downward pushed to compress the coiled compression spring 118 and downward move the shuttle 128. Such lowering of the shuttle 128 permits the passage 130 to communicate with the pump passage 136, so that pressure or hydraulic oil from the hydraulic pump 138 is fed through the pump passage 136, passage 130 and passage 134 to the output port 106.
At this time, a back pressure from the side of the output port 106 acts on a pressure receiving surface 144 which is a lower end surface of the shuttle 128, so that the back pressure and elastic force of the coiled compression springs 114 and 118 are balanced with each other to control a position of the shuttle 128 and therefore hydraulic oil discharged from the output port 106. When the back pressure acting on the pressure receiving surface 144 of the shuttle 128 is increased, the shuttle 128 is pushed to a position at which the passage 132 of the shuttle 128 communicates with the tank passage 140, resulting in hydraulic oil being returned through the passages 132 and 140 to the tank 142.
As can be seen from the foregoing, the conventional input apparatus or pilot valve constructed as described above is adapted to output hydraulic pressure of a predetermined level depending on the amount of operation of the lever 124 to the output port 106.
Unfortunately, the input apparatus completely fails to control its output by means of an external signal such as a hydraulic signal output from a different or external hydraulic control system or the like, and thereby fails to operate in association with the external hydraulic control system.
The present invention has been made in view of the foregoing disadvantages of the prior art.
Accordingly, it is an object of the present invention to provide an input apparatus which is capable of concurrently outputting both a hydraulic signal and an electrical signal.
It is another object of the present invention to provide an input apparatus which is capable of permitting an operator to readily accomplish both hydraulic control and electrical control in association with each other substantially without requiring skill.
It is a further object of the present invention to provide an input apparatus which is capable of concurrently accommodating itself to an any external signal from a different or external hydraulic control system or the like.
It is still another object of the present invention to provide an input apparatus which is capable of concurrently responding to both a signal generated by itself and an external signal fed thereto.
In accordance with one aspect of the present invention, an input apparatus is provided which comprises a control section, a body, a plurality of sets of push rods arranged in the body in a manner to correspond to a plurality of actuators and commonly operatively connected to the control section, the sets each comprising two push rods, a block and elastic means arranged in the body and operatively connected to each of the push rods, a spool arranged in the body and operatively connected through the block and elastic means to each of the push rods, the body being formed therein with a hydraulic oil feed passage, the spool being formed with a passage, whereby the control section is pressedly operated to force each of the spools through the push rod, block and elastic means to permit the hydraulic oil feed passage of the body and the passage of the spool to communicate with each other to feed the actuator with hydraulic oil and balance force generated due to flowing of hydraulic oil and acting to forcedly return the spool with elastic force of the elastic means to position the spool depending on the amount of operation of the control section, to thereby feed hydraulic oil in an amount corresponding to the amount of operation of the control section to the actuator. The input apparatus is featured in that it further comprises electrical load sensors for detecting the amount of operation of the control section to generate an electrical signal corresponding to the amount of operation of the control section.
In accordance with another aspect of the present invention, an input apparatus is provided which comprises a control section, a body formed with a pump passage and an output port, push rods arranged in the body and operatively connected to the control section, elastic means arranged in the body and operatively connected to each of the push rods, a shuttle arranged in the body and operatively connected to each of the push rods, the shuttle having a pressure receiving surface and being formed with a passage, whereby pressing operation of the control section causes the shuttle to be moved through the push rod in one direction against the elastic means to permit the passage of the shuttle with the pump passage of the body, resulting in feeding hydraulic oil from a hydraulic pump through the shuttle to the output port of the body and balancing a back pressure acting on the pressure receiving surface of the shuttle through the output port and elastic force of the elastic means with each other to determine a position of the shuttle and therefore a hydraulic pressure output through the output port depending on the amount of operation of the control section. The input apparatus is featured in that it further comprises a pilot section for exerting force which permits the shuttle to be moved against the elastic means and the pilot means is fed with a signal from a different hydraulic control system.